Aviation spark plug



March 26, 1940. 1 DEWNE 2,194,695

AVIATION SPARK PLUG (RADIO SHIELDED) Filed NOV. 5, 1938 INVENTOR.

Patented Mar. 26, 1940 UNITED STATI-:s

PATENT OFFICE AVIATION SPARK PLUG (RADIO SHIELDED) Julius Devine, Cleveland, Ohio Application November 5, 1938, Serial No. 239,161

2 Claims. (Cl. 123-169) The purpose of this invention is to eliminate gas and current leakage which are the chief destructive elements responsible for inefficient motor performance.

Leakage of hot gases through the insulator ultimately destroys the insulator, causing lack of combustion, loss of compression.

Current leakage resulting in loss of combustion, fouling, preignition, low pressure firing, carbonization, missing and short life of the plug.

Metal expanding away from the insulator under heat when the plugs are in actual operations adds more fury to above conditions.

The compression of hot gases from the motor cylinder will then pass through `the joints of the spark plug core without the least resistance, though the metal expansion might be as little as 0.001 inch, but under high compression a gas leakage of 5 to 10 c. c. per minute will result.

Spark plugs built in accordance with my appended claims eliminate the above difficulties resulting in long life of the plug and efficient motor performance.

Referring to drawing:

Fig. 1 is. a cross-section of a spark plug comprising three parts when screwed together.

Fig. 2 represents Fig. l showing the threeparts partly exposed, namely, the shield, housed core and shell.

Fig. 3 shows a modied two piece plug screwed together.

Fig. 4 shows the groove in the head of the center electrode.

Fig. 5 shows somewhat of another exposed similarity to Figs. 1, 2 and-3. A

Referring now to drawing of above views:

The spark plug comprising a central electrode 6 surrounded by a mica insulator 1 projecting within groove and filler 8 of electrode head 9, said f'lller comprising hard metal wedge or a heat dissipating material, compressed mica washers I0 or any other suitable material surrounding said insulator 1 on the lower end and resting partly on top of the electrode head 9 and filled groove 8.

The outside rim II of the electrode head 9 is clamped together to completely fill the groove 8 by forcing the rim II against the illler and lower end of insulator 1 projecting within said groove 8. On top of the lower washers III, as in Figs. 1, 2 and 5, there is seated a gland or a housing I2 externally smooth and angled.

The said angled gland I2 as shown in exposed ing angle of shell I6 and screwed together with shield I6, shown in the completeA assembly of Fig. 1.

The seat of the shield I6 is pressing on top of housing I2 when screwed together with shell I5, for the purpose of effecting a gastight seal be- 5 tween the housing I2 and said shell I5.

The gland or housing I2 is made of steel, copper or any suitable material and has a portion removed from its top or bottom forming a circular triangular void and leaving a thin wall I9 adjacent the insulator 1, a steel or copper wedge I1, or some heat dissipating material is then forced into the void of wedge space I1, forcing the remaining inner thin wall I9 of the housing I2 against the insulator 1.

In Fig. 3 there is a two piece spark plug. The shield I6 in combination with gland 2| is screwed together with internal threads of shell I5. The wedges I3 and I4 of Fig. 3 are pressed into the gland 2I from both sides against an independent soft or copper sleeve I8 to force the said sleeve against the insulator.

Fig. 5 shows an angular gland I2 or housing outwardly smooth resting on top of lower washers I0, an independent soft metal sleeve or copper sleeve 23 surrounding said insulator 1 of Fig. Y5, a copper or a steel wedge ring I1 is forced into the space between the said independent soft sleeve 23 and said housing I2 of Fig. 5 for the purpose of forcing the said sleeve 23 against the insulator.

In Figs. 1, 2 and 5 a stack of compressed insulatingv washers 24 surrounding the upper part of the insulator 1 around the upper part of l'the electrode 6 on top of the said electrode 6 shows a drilled hole 25, which is used to roll the edges outward if desired, for the purpose of holding down a small metal cap 26 when said cap is forced down on top of the mica washers 24.

The shell I5 is provided with four inclined electrode points 28 projecting into proper spaced re- 40 lationship tothe firing tip 22.

The shield I6 is mica lined inside 21, the lower end'of the said mica lining 21 is resting on an inner shoulder 29, the bottom of said shoulder 29 is continuously pressing on top of wedge I1 45 and on top of housing I2 when the seat of shield I6 is screwed together with internal thread of shell I5, as in Fig. 1.

'Ihe purpose of groove 8 is to seal the lower ends of the mica insulator 1 to effect a gastight 50 seal, that ls to prevent the hot gases from entering into between the insulating sleeve 1 and the electrode 6. as well as between the mica insulator itself.

The purpose of the wedge I1 in housing I2 is 55 to keep the remaining thin wall i9 of Figs. 1, 2 and 5 from expanding away from the insulator under heat in actual operation of the motor.

The washers 24 compressed to 40,000 pounds per square inch resting partly on top of the ller 8, and wedge i1, of head 9, likewise the washers I0 compressed to approximately 40,000 pounds per square inch resting on groove and filler 8 `\Will keep a continuous gastight seal in said groove.

Another Wonderful feature is that the mechanic is able at all times, if ever at all required after long service, should a small leak occur, he can again tighten up the plug by simply adding an additional turn on hex 30 which in turn adds pressure on wedge Il, thus forcing Wall i9 closer to the insulator 'l Without injury to said insulator or washers I0 and 24.

Once the proper dimensions and proper tooling has been obtained, and the plug properly constructed, it then becomes simple and cheap in its construction.

What I claim is: f

1. In a spark plug, an electrode, insulation surrounding said electrode, a at bottomed cylindrical nut, an annular wedge shaped housing member having an annular wedge shaped receiving recess surrounding said insulation, a at top wedge shaped ring, adapted to substantially fit into said recess, said housing member and wedge ring made of metals having different rates of expansion, said housing member being located between said shell and said cylindrical nut, and so arranged that when these two members are screwed together the cylindrical nut will longitudinally force the wedge ring into the housing so that one wall of the annular housing will be forced against the insulation and the other against the shell, and due to the longitudinal contact of cylindrical nut and wedge ring the latter will be prevented from being dislodged when under severe vibration.

2. In a spark plug, an electrode, insulation surrounding said electrode, a shell and a cylindrical nut in threaded relation, an annular wedge shaped housing member having an annular wedge shaped receiving recess surrounding said insulation and resting upon said shell, a wedge shaped ring adapted to substantially t into said recess, said cylindrical nut having its lower end adapted 'to be in direct contact with the top of the wedge so as to prevent the dislodgement of the wedge when the plug is in operation.

JULIUS DEVINE. 

